If, when presented with a mirror, an animal recognizes that the reflection belongs to him or herself, then the animal is considered to have shown an awareness of him/herself. The test is performed by surreptitiously applying a mark to part of the animal’s body (e.g., the forehead) that is only visible in the mirror. If, on seeing their reflection, an animal responds to the mark by either touching it or trying to remove it from their body, they pass the test.

Until recently, the only creatures to conclusively show mirror self-recognition were mammals: humans, great apes, dolphins and elephants. Then, in August 2008, a team of German researchers demonstrated this advanced cognitive feat by secretly placing a colored adhesive dot on the throats of several magpies. On seeing their reflection, some birds tried to remove the dot by scratching with their feet; others tried to pull it off with their beak. Black dots, which were camouflaged against the magpies’ black neck feathers, were ignored.#

The magpie study is an important advance in what we know of the evolution of self-awareness, because it shows this capacity has evolved independently in a separate lineage. The special significance of this finding is that brains of birds have evolved differently from those of mammals. Lacking a neocortex—that prominent, often convoluted part of the mammalian brain—birds’ brains have instead undergone proliferation in the paleocortex, which in mammals is not responsible for cognition. In 2005, a team of experts announced a makeover in the naming of bird brain parts to reflect the recognition that birds’ well-developed paleocortex endows them with cognitive skills akin to mammals.

As primatologists Dorothy Cheney and Robert Seyfarth note in their book Baboon Metaphysics: The Evolution of a Social Mind, proving that an animal has a theory of mind is very difficult because in most cases their behavior can be explained by relatively simple behavioral contingencies. Dogs who slink guiltily after tipping over the garbage may also do so if another dog did it, so the dog may merely have learned that when garbage is tipped over, people begin to shout. The failure of monkeys to “pass’ the well-known mirror self-recognition test has fostered the belief that these animals have no concept of self.

While the veracity of that conclusion can be debated (failure at mirror self-recognition needn’t mean lack of self-awareness), a recent study of macaques suggests that monkeys understand other beings as agents with their own perspectives and intentions. Macaques held captive at the University of Parma, Italy, were shown a goal-directed task in which a woman reached over a tall obstacle to pick up a toy resting on the other side. On average, this rather predictable scene caused the monkeys to gaze at the woman’s face for only seven milliseconds. However, their average gaze increased to around 18 milliseconds when the woman performed the same movements with no barrier present.

In human children presented with the same scenes, prolonged gazing is thought to indicate that the children have some understanding that the observed person is a rational being with her own intentions, and the same conclusion is drawn from the macaque study. When observing the gazes and actions of other animals, brain activity in monkeys and humans is similar, which provides further support that there is some form of attribution going on.